Detection and molecular characterization of the rice root-knot nematode Meloidogyne graminicola in Italy

Abstract

The rice root-knot nematode Meloidogyne graminicola was detected in North Italy attacking roots of rice plants in lowland and upland fields. This nematode was previously reported only in South and Southeast Asia, China, South Africa, United States, Columbia and Brazil attacking rice and wheat. The present study provides an integrative diagnosis of the nematode on the basis of morphological and molecular data by sequencing the SCAR species specific marker, the ITS region and the partial mitochondrial coII-16srRNA genes. Morphological and morphometric traits of the new intercepted population of M. graminicola agree with the original description. The diagnostic SCAR marker was amplified showing the expected size fragment and unequivocally identified the Italian population as M. graminicola. Sequence analyses of ITS and coII-16SrRNA confirmed this identification. Sequence comparison of both molecular markers among Italian M. graminicola populations from lowland and upland rice fields revealed 100% identity. Phylogenetic analysis based on the ITS and coII-16SrRNA sequences revealed that Italian M. graminicola formed a well supported cluster with M. graminicola populations from GenBank confirming the high intraspecific variability among all populations. No correlation between genetic variability and geographic origins occurred. Furthermore, the phylogenetic trees suggest a common ancestor for most of the facultative meiotic parthenogenetic Meloidogyne species.